1. Field of the Invention
This invention most generally relates to a controlled labyrinth heat exchanging oil nozzle assembly which may be used in conjunction with a heat exchanging device for heating a fluid such as air. The heat exchanging device provides heated air by conduction of heat, at a plurality of locations, from a combustion gas space to the fluid. Such heat exchanging device as is disclosed in the application incorporated herein by reference thereto. Even more particularly the invention relates to a controlled labyrinth heat exchanging oil nozzle assembly which is use along with a flame producing nozzle within an oil burning heating system wherein the nozzle assembly comprises a block, the temperature of which is controlled or controllable and in which there is at least one cylindrical bore (preferably two bores are provided) into which director plugs are specially inserted. The block, the bore or bores and the flow director plug or plugs are designed to provide a fuel flow passage which undulates upward and downward thereby increases the dwell time or the time during which fuel is within the block and also creating substantial surface area through which heat is transferred or transferable from the block when it is heated to the fuel flowing in such an undulating manner therethrough. There is also provided an air passage within the block and which provides air at appropriate pressure to an air atomizing flame producing nozzle. The air is also heated by the block so that the air is at an appropriate and desirable temperature when it mixes with the fuel at the nozzle. All of these features are achieved along with providing for total and easy access to virtually all of the primary heat exchange surfaces and the surfaces of the fuel passage for the purpose of inspection and thorough cleaning without the necessity of taking the assembly "off line". It is also very easy to remove oil and residue of the fuel/oil from the passage by removing the nozzle and appropriately plugging the nozzle end of the block then providing air or gas pressure through the air passage which is diverted from the nozzle end back through the undulating fuel passage toward the block fuel input end where, with the fuel supply line removed, the waste oil and the residue that was residing in the passage may be collected and discarded. This operation can be achieved without removal of the director plugs. All such elements and the respective geometries, provide for controlled residence time for the fuel within the heated block thereby uniformly transferring or exchanging heat from the block to the fuel flowing therethrough to a commercial type atomizing nozzle.
2. Description of the Prior Art
In order to be able to burn waste oil products in an efficient and ecologically sound manner, it is critical that the combustion efficiency be within well defined specifications. It is required that the efficiency be not less than 75% as measured according to industry accepted standards of testing and that the residuals emitted be as completely oxidized as possible at this efficiency level. The maintenance must be low, the combustion efficiency high, and there must be high thermal energy transfer in order that the system be acceptable for such use. In particular, the design of a device for the burning (rapid oxidation) of contaminated waste oils should have a smooth uniform, constant, controlled flow of combustion gases throughout and there should be no abrupt direction changes of the gases while they are at the highest temperature, i.e., prior to the combustion gases giving up most of the heat to the fluid. This is necessary to uniformly deposit, within the device those noncombustibles inherently generated by this process. When this is accomplished the heat exchange degradation process is more nearly uniform preventing premature heat exchange loss in any given area.
It would be desirable and advantageous to have a heat exchange device which would be capable of burning waste oil products efficiently and in a manner which would allow easy cleaning of the burner unit and the heat exchanger and the fuel oil nozzle assembly. It would also be desirable to have a nozzle assembly which could be used in the burning of waste oil as a fuel which oil has substantial residues. Such an assembly must be able to elevate the temperature of the fuel oil and the air which will be mixed with the fuel at the atomizing nozzle and at the same time have a reasonable volumetric size. In addition it is important that a nozzle assembly be provided which does not trap residue from the waste oil, which is easily and efficiently cleaned and in which the temperature of the oil/fuel/waste oil can be elevated and controlled prior to it being mixed and atomized at the tip of the nozzle. Further, there should be provided means for preventing or controlling the "dripping" at the nozzle tip at shutdown. Such control is very important so that residue buildup in the furnace, below the nozzle input region, is kept to a minimum. None of the prior art devices have been able to combine in reasonable and acceptable ways the features which will increase the fuel dwell time by increasing the effective length of the passage from the fuel line through the heating device and then to the nozzle in order to raise the temperature of the fuel to the desired level, along with providing for ease of inspection and cleaning of the fuel passage through the heating device or the block.
It is also very important that the device can be quickly, easily and thoroughly cleanable. In the burning of waste oil those noncombustibles contained in the waste oil deposit in the combustion chamber. Additionally, the temperature of the fuel oil being provided at the atomizing nozzle must be controlled at an elevated temperature. To heat the fuel it must be resident within a heating block sufficiently long to allow the fuel to reach the desired temperature. This "dwell time" can be achieved using helical travel or other ways to increase the distance from the fuel input to the heating block to the nozzle end of the block. However, voids are frequently created which create dripping at the nozzle end when the burner shuts down. Additionally, the residiue or the residuals present in waste oil will tend to collect or settle into low regions of the oil passage. This residue will build up rapidly and the assembly must be accessible for inspection and for cleaning. Present nozzle assemblies do not provide the combination of easy access for inspection and cleaning along with sufficiently long dwell time. It is simply not possible or it is at best very inconvenient and difficult to inspect and thoroughlyclean such assemblies. In order to maintain the needed and desirable high efficiency of a system, the deposits within the nozzle assembly must be easily and frequently removed or removed when an inspection shows an unacceptable level of residue.
The instant invention especially when it is used in conjunction with the heat exchanger disclosed in Applicant's U.S. Pat. No. 4,905,661 and with the heat exchanger disclosed and claimed in the referenced U.S. Patent Application, accomplishes such objectives. In accomplishing the objectives of efficient burning of waste oil, the device is also very effective and efficient and very maintenance free when burning conventional heating oil. Applicant is not aware of any heat exchanger devices or assemblies presently available which meet the necessary criteria for the proper and effective burning of waste oil products coupled with the ability to expose completely and in total all surfaces for necessary, periodical inspection and/or mechanical cleaning. Nor is Applicant aware of a device which incorporates all of these desirable features within the relatively small volumetric configuration possible with this invention. In fact Applicant is unaware of any such units available which have the advantages and characteristics described that burn regular fuels such as heating oil and/or gas.
Some inventions related to the instant invention and disclosed in the following United States Patents have been studied. The following is a brief description and discussion of these related inventions.
Wilson, U.S. Pat. No. 4,905,661, a heat exchanger with which the present invention may be advantageously used, discloses cylindrical heat exchanger in which the flame is introduced into the device about perpendicular to the axis of the flow of both the combustion gases and the air which is being heated in the device. In the patented device, the combustion gases flow in a helical path around the inner shell through which air to be heated flows in an axial path through the device and the flame is introduced into the combustion chamber in a direction perpendicular to the axis of the heat exchanger.
Niederholtmeyer, U.S. Pat. Nos. 4,392,820 and 4,460,328 describe very complicated systems and methods for use in burning conventional heating oil and waste oil in combination. There are two distribution networks which communicate with a heating box. Neither of these patents disclose a structure which has the features and the advantages of the structure disclosed in the instant application.